There is a good global pomodoro timer for working and chating with others. Every 30 minutes a global pomodoro starts. The design is also clean and minimalist.
https://pomodorr.io
I think the idea of chatting during a Pomodor session is strange, but I do appreciate the opportunity to work with friends and the social accountability it provides. I believe it would be beneficial if the service offered private rooms. Additionally, it would be great if there was a built-in feature for users to give positive feedback, such as a 'like' button.